1. Field of the Invention
The present invention relates to structures for closing a cavity of a hollow structural member and for reinforcing the hollow structural member (hereinafter "structures for closing and reinforcing a hollow structural member"), and to methods for closing the cavity of the hollow structural member and for reinforcing the hollow structural member (hereinafter "methods for closing and reinforcing a hollow structural members"). More particularly, the present invention relates to structures and methods for closing and reinforcing a closed box-like hollow structural member constructed from a plurality of plates, such as a front pillar and a center pillar of a vehicle, to increase the damping and sound insulating powers of the hollow structural member and to increase the strength and rigidity of the hollow structural member.
2. Description of the Related Art
FIGS. 8(A), 8(B), 9(A) and 9(B) show examples of a known structure for closing cavities 206a and 206b of a hollow structural member or pillar 201 of a vehicle body and for reinforcing the pillar 201. As shown in these drawings, the pillar 201 is constructed from an inner panel 202, an outer panel 204 and an Intervening reinforcement panel 208. The cavities 206a and 206b are formed in the spaces between these panels. In this structure,four plate-like foamable pads 221 are initially disposed in the cavities 206a and 206b in an unfoamed state. In this state, the unfoamed pads are in a compressed state and can be expanded by exposing to heat. The foamable pads 221 each have a desired length and are adhered, by adhesive, to the inner surfaces of the inner 202 and outer panels 204 and both surfaces of the reinforcement panel 208, respectively.
As shown in FIG. 8(B), obstruction plates 231 are disposed in the cavities 206a and 206b. The obstruction plates 231 are secured to the inner panel 202 and to the reinforcement panel 208 by spot welding or other such methods. The obstruction plates 231 have profiles that substantially conform to the transverse cross-sectional configurations of the cavities 206a and 206b, respectively. As will be appreciated, the foamable pads 221 are positioned adjacent to the obstruction plates 231.
As shown in FIGS. 9(A) and 9(B), when the pillar 201 is heated by external heating, the foamable pads 221 expand to produce foamed products 222. As will be recognized, the obstruction plates 231 may be used to effectively prevent the foamable pads 221 from expanding downward. The foamed products 222 thus formed fill the cavities 206a and 206b and reinforce the pillar 201, thereby increasing the damping and sound insulating powers of the pillar 201 and increasing the strength and rigidity of the pillar 201.
However, in the above-described known structure, to sufficiently increase the strength and the rigidity to the pillar 201, the foamable pads 221 must be significantly increased in size, so that the foamed products 222 may extend to greater than a desired length in the cavities 206a and 206b. Additionally, the foamable pads 221 preferably should be made of special foamable materials, so that the foamed products 222 have sufficient rigidity or hardness when they are cured in the cavities 206a and 206b. These requirements may lead to increased costs.
Further, in the known structure, the foamable pads 221 must be adhered to the inner and outer panels 202 and 204 and the reinforcement panel 208 by adhesive prior to heating. The obstruction plates 231 also must be mounted on the inner panel 202 and the reinforcement panel 208 prior to heating, which are rather troublesome and time-consuming operations.
Further, the pillar 201 may have some un-painted portions, which un-painted portions result from the fact that the foamable pads 221 are adhered to the inner and outer panels 202 and 204 and the reinforcement panel 208 prior to painting. Such un-painted portions on the pillar 201 are therefore susceptible to corrosion.
Moreover, as generally shown in FIG. 9(B), the inner panel 202 of the pillar 201 is formed with a plurality of apertures 232 (only one of which is shown) for attaching an ornament or other decorative member (not shown) to the pillar 201. In the known structure, the apertures 232 may be closed by a portion 222a of the foamed products 222, because the foamed products 222 may expand over a considerably prolonged extent. Closure of the apertures 232 by the foamed products 222 may prevent engagement pins (not shown) provided on the ornament from engaging the apertures 232, thereby preventing the ornament from being mounted on the pillar 201.